Day 09

day09/part1.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+
+import numpy as np
+import scipy.ndimage.filters as filters
+import scipy.ndimage.morphology as morphology
+
+
+arr = np.array([[int(n) for n in line.strip()] for line in open("input.txt")])
+
+# https://stackoverflow.com/questions/3986345/how-to-find-the-local-minima-of-a-smooth-multidimensional-array-in-numpy-efficie
+neighborhood = morphology.generate_binary_structure(len(arr.shape), 1)
+local_min = (filters.minimum_filter(arr, footprint=neighborhood) == arr)
+local_max = (filters.maximum_filter(arr, footprint=neighborhood) == arr)
+local_min_without_plateau = np.logical_and(local_min, np.logical_not(local_max))
+local_min_locations = np.where(local_min_without_plateau)
+local_min_values = arr[local_min_locations]
+
+print(sum(local_min_values)+len(local_min_values))